1. Field of the Invention
This invention relates to an improved roller hinge unit for an articulated rollup door and, more particularly, to a roller hinge unit including a spring for centering the articulated roll-up door.
2. Description of the Related Art
Truck doors of the type commonly referred to as roll-up or upwardly acting conventionally employ multiple door sections which are hinged together, with each door section being rollably supported on a pair of L-shaped tracks for low friction upward movement from a substantially vertical closed position into a substantially horizontal open position. Each door section has a roller hinge unit disposed adjacent the side edges thereof, which units not only hinge the adjacent door sections for relative pivoting movement therebetween, but additionally support a roller shaft which mounts a roller that rolls on the stationery L-shaped track. The U.S. Pat. No. 2,257,513 shows such a construction, for example.
The roller hinge unit conventionally employs a pair of hinge leaves fixed to the adjacent door sections and disposed in juxtaposed relationship. The hinge leaves support and form a hinge socket in which a roller shaft axially slides to compensate for track variation. The stem has a roller on a distal end thereof for rolling on the adjacent track.
One recent roller hinge unit has a bushing with a closed end that mounts a spring to bias the stem of the roller outwardly. The bushing is retained in the hinge by fingers which form the socket for the bushing. The fingers are bent into a semi-cylindrical shape to form the bushing socket after the socket has been positioned in the hinge. The fingers must be pliable to bend and are supported on one end only. This construction results in a tweak hinge because the fingers can deform under stress and the socket can fall out of the socket.